Peripheral Component Interconnect (PCI) is a computer bus design standard for connecting peripheral components to computers. A PCI bus typically routes signals between a central processing unit (CPU), various other chips on the motherboard, and cards that are plugged into PCI bus slot connectors. The PCI bus, however, is independent of the CPU chip implemented in a computer system. Thus, the PCI bus is adapted for use in many different kinds of computers or other high-tech hardware. Earlier versions of the PCI standard included PCI 2.2 and PCI-X.
PCI Express is the third generation of PCI architecture. PCI Express offers higher input/output (I/O) bandwidth than its predecessors. Traditional PCI attributes, such as its usage model and software interfaces, are maintained. However, the previous parallel bus implementation has been replaced by a link-to-link serial interface. Further, a split-transaction protocol is implemented with attributed packets that are prioritized and optimally delivered to their target.